Hydraulic servo governor



United States Patent Stephen F. Glassey East Peoria;

Fredrick W. Pfeiffer, Peoria Heights; Harold C. Davidson, East Peoria,Illinois 172] lmentors [21] Appli No. 799,214 [22] Filed Feb. 14, 1969[45] Patented Oct. 20, 1970 Caterpillar Tractor Co. Peoria, Illinois acorporation of California [73] Assignee- [54] HYDRAULIC SERVO GOVERNOR 5Claims, 3 Drawing Figs.

91/458 511 lnt.Cl ..F15bl3/l6 so FieldofSearch 91/458 [56] ReferencesCited UNITED STATES PATENTS 1,748.326 2/1930 Birmann 91/366 3,002,50210/1961 Szydlowsk' 91/366 3145,624 8/1964 Parks et a1. i t 1 1 1 91/366Primary ExaminerEdgar W. Geoghegan Almrncy- Fryer, Tjensvold, FeixPhillips and Lempio ABSTRACT: A hydraulic servo governor for regulatingen gine speed having rotating flyweights acting against an adaptersecured for rotation with a valve member reciprocahly disposed in acylindrical bore. A member seating a spring which tends to oppose theeffect of the flyweights is rotatably secured for longitudinal motionwith the valve and adapter by means ofa thrust bearing.

Patented Get. 20, 1971) 3,534,660

Sheet 1 of 2 INVENTORS LO STEPHEN F GLASSEY FREDERICK W. PFEIFFER BYHAROLD C. DAVIDSON W) {M1 w 2% #411- ATTORNEYS Patented Oct. 20, 19703,534,660

Sheet 2 of2 J l &

INVENTORS STEPHEN F. GLASSEY FREDERICK W PFEIFFER BY HAROLD C. DAVIDSONHYDRAULIC ssnvo GOVERNOR The present invention is described withreference to a hydro-mechanical governor of the type described in U.S.Pat. Nos. 3,145,624 and 2,961,229 issued respectively on Aug. 25, 1964to J. H. Parks et al. and on Nov. 22, I960 to .l. H. Parks, both patentsbeing assigned to the assignee of the present invention.

Governors for controlling engine speed commonly operate through theinteraction of flyweights and an opposing governor spring. Theflyweights are mounted on a member which rotates at a speed proportionalto the engine speed. The flyweights assume a position consistent withthe centrifugal force supplied by the rotating member and therebydetermine the position of a fuel control member such as an engine fuelpump rack bar. Constant speed operation is achieved when the rack bar ispositioned to supply fuel to the engine to operate it at a speed whichrotates the flyweights with sufficient centrifugal force to counteractthe opposing governor spring.

In certain engine applications, for example, where the governor isemployed to regulate the speed of a diesel engine driving a generator,it is necessary to utilize a governor which will rapidly respond to aload change without excessive hunting. The term hunting," as hereemployed, refers to a condition which exists when the engine load issuddenly increased or decreased. The governor, in attempting tocompensate and maintain a constant speed, often overshoots the set speedand then, in returning toward the set speed, undershoots the set speed.This hunting action continues in diminishing cycles until the governorstabilizes. If the governor continues to oscillate or hunt for too longa time, it is detrimental to the operation of the generator.

Such governors commonly comprise a cylindrical control valve which iscaused to move longitudinally in a cylindrical bore and position thefuel pump rack bar according to the interaction of flyweights and aspring. One cause or contributing factor to the hunting conditiondescribed above is the additional force required to initially set thecontrol valve in longitudinal motion while such motion is resisted bystatic friction between the control valve and the cylindrical bore inwhich it is disposed.

The present invention eliminates this static friction and thus reducesthe hunting tendency of the governor and improves governor response bypermitting substantially free and independent rotation of the controlvalve within its cylindrical bore.

The present invention offers particular operating advantages whenembodied within a governor of the type disclosed in U.S. Pat. No.3,145,624. As disclosed in that patent, the control valve is associatedwith a hydraulic servo unit which assists in positioning of the fuelpump rack bar. The hydraulic servo unit substantially reduces the amountof force exerted through the control valve. The elimination of staticfriction accordingly reduces hunting in the governor by a greaterdegree.

In addition, the present invention permits generally free andindependent rotation of the valve to increase responsiveness of thegovernors. This feature tends to reduce wear in those parts of thegovernor which are associated with the control valve, thus enabling thegovernor to maintain an accurate setting over long periods of operation.

Other objects and advantages of the present invention will be apparentfrom the following description and the accompanying drawings.

In the drawings:

FIG. 1 is a side view, with parts in section, of a hydromechanicalgovernor which embodies the present invention;

FIG. 2 is an enlarged fragmentary view taken from FIG. 1 to illustratein detail a portion of the governor with which the present invention isparticularly concerned; and

FIG. 3 is a view taken along section line Ill-III of FIG. 2.

As illustrated in FIG. 1, a governor 11 controls the longitudinalposition ofa fuel pump rack bar 12 and accordingly the LII adjustment offuel pumps, one of which is illustrated at 13, through a segment gear [4associated with each fuel pump and interacting with the rack bar. Thefuel pump is preferably illustrative of a diesel engine driving agenerator. The governor is enclosed by a governor housing 16 and a fuelpump housing 17 and comprises flyweights l8 pivotally mounted on acylindrical carrier 19 by pins 21. The carrier is mounted for rotationabout a cylinder 22 affixed to the fuel pump housing. The cylinder 22forms gear teeth as indicated at 23 to provide a pinion in constant meshwith a drive gear 24 secured to a shaft 26 which forms a part of thetiming gear train of the engine.

The flyweights move outwardly under the influence of increasing enginespeed so that their radially inwardly extending arms 27 act against andtend to cause leftward motion of a generally tubular adapter 28 and acontrol valve 29 secured thereto by a pin 31. Leftward motion of theadapter 28 and valve 29 is resisted by a spring 32 acting against avalve seat 33 associated for longitudinal motion with the adapter andvalve 29 in a manner described below in detail. Thus, when engine speedis increasing, the flyweights move outwardly and their radial arms 27act against the adapter to overcome the spring 32 to cause leftwardmovement of the control valve. Conversely, when engine speed isdecreasing, the flyweights move inwardly and the spring 32 tends toreturn the adapter and control valve to their rightward positions.

A servo system 34 is associated with the control valve and positions therack bar in response to longitudinal movement of the control valve. Theservo unit comprises a piston 36 disposed for longitudinal motion in thefixed cylinder 22 and within a fixed sleeve 37 while its right end 38 isjoined to the fuel pump rack bar 12. The control valve 29 is disposedfor longitudinal motion within a bore 40 formed by the piston 36. Thepiston has a flange or piston head 39 midway along its length forming anannular cavity 41 within the left end of the fixed cylinder 22 andenclosing an annular cavity 42 between the right end of the fixedcylinder 22 and the fixed sleeve 37. Hydraulic fluid is introduced intothe annular cavity 42 through a conduit 43 to act against the right sideof the piston head and to be communicated to the piston bore 40 by aconduit 46 in the piston head. The piston head has a conduit 47communicating the annular cavity 41 with an annular recess 48 in thepiston bore. The control'valve defines a first annular slot 49 and arightwardly disposed second annular slot 51 which is communicated to afluid drain formed by internal bores 52 and 53 in the control valve andfuel pump rack bar respectively.

In operation, the piston 36 tends to follow longitudinal movement of thecontrol valve and to position the rack bar accordingly. As the controlvalve is moved rightwardly, the annular slot 49 completes a fluid pathfrom the annular cavity 42 through the conduit 46, the annular recess 48and the conduit 47 into the annular cavity 41 wherein fluid pressurebuilds up to act against the piston head and move the piston and fuelpump rack bar to the right. As the control valve is moved leftwardly,the annular slot 51 is aligned with the annular recess 48 and permitsfluid from the annular cavity 41 to pass to drain through the conduit47, the annular recess 48 and the internal bores 52 and 53. Uponreduction of fluid pressure in the annular cavity 41, hydraulic fluidpressure in annular cavity 42 acts leftwardly against the piston head tocause leftward movement of the piston and rack bar until the annularslot 51 is no longer in communication with the annular recess 48.

A flanged control rod 54 penetrates a hole 55 formed in the left end ofthe spring seat 33 and extends leftwardly therefrom to act against aspring blade 56 by means of a plate 57 secured upon the control rod toallow additional fuel to be injected into the engine to provide thetorque rise required from the engine under certain conditions.

To permit adjustment of the governor and the speed at which the engineis to be controlled, the spring 32 is retained at its left end by aslidable spring seat 58. A manually adjustable lever 59 acts against thespring seat 58 to control its longitudinal position and thus control theforce which the spring 32 exerts upon the valve seat 33, the adapter 28and the control valve 29. The manner of operation of the lever'59 isfully described in US. Pat. No. 2,961,229.

The present invention is concerned with improving response of thecontrol valve 29 and the servo unit 34 to variations in engine speed andcorresponding repositioning of the flyweights 18. This problem isbelieved to be solved by the present invention in a novel manner whichaffords additional operating advantages for the governor.

As noted above, the valve 29 is secured for rotation with the adapter28. When the flyweights are rotated and their arms 27 act on theadapter, the adapter 28 and valve 29 are accordingly both rotated alongwith the flyweights. Constant rotation of the valve 29 within the bore40 during operation of the governor eliminates static frictiontherebetween which tends to resist initial motion ofthe valve in eitherdirection.

Additionally, the present invention further improves response, reduceswear and assures more uniform operation of the governor by arranging thevalve 29 and adapter 28 for generally free rotation in response to theflyweights. With the small adapter 28 being the only component which isrotated with the valve, the rotating mass of the valve 29 is minimizedand its responsiveness is further reduced.

The interconnection between the spring 32, flyweights 18 and valve 29substantially eliminates rubbing engagement between relatively rotatingparts except for that between the valve 29 and the bore 40. This in turnprevents wear in the governor which would otherwise tend to causeundesired variation in the engine speed setting established by thegovernor.

The features which accomplish the improved operating characteristicsdiscussed above are best seen in FIGS. 2 and'3. Referring to those FIGS.as well as FIG. 1, a ball bearing assembly 61, preferably of a type fortransferring axial thrust, is

arranged between the seat 33 and valve 29. The bearing has an inner race62 secured to an end of the valve 29. its outer race 63 is secured to acylindrical end portion 64 of the spring seat 33. The end portion 64also has a flange 66 for supporting the spring 32.

Since the bearing 61 provides an almost frictionless coupling betweenthe valve 29 and spring seat 33, the valve 29 and adapter are capable offree and independent rotation except for contact between the valve 29and bore 40. In addition to permitting relatively frictionless rotation,the bearing also couples the spring seat 33 and valve 29. Thus,reciprocating interaction of the flyweights 18 and spring 32 is impartedto both the valve 29 and the control rod 4 To facilitate assembly of thegovernor and to adapt the present invention to existing governors, theend portion 64 is formed with two separable segments 33a and 33b. Thespring seat 33 may be manufactured as a single piece and then cut toform the two segments. With the two segments arranged about the valve 29and bearing 61, they are secured together by a spacer 67 and a snap ring68. The inner bearing race is also secured .to the adapter 28 by a snapring 69 as best seen in FIG. 1.

We claim:

1. in a governor of the type having flyweight means interacting with aspring to longitudinally position a control valve within a cylindricalbore formed in a housing and hydraulic servo means responsive to thepositioning of the control valve for establishing engine speed, thecombination comprising:

an adapter secured for rotation with the control valve, the

adapter being disposed for interaction with the flyweight means and forrotating the control valve together with the flyweight means;

a seat member upon which the spring acts; and

bearing means arranged to effectively'secure the spring seat and controlvalve together for longitudinal motion and provide for properinteraction of the spring and flyweights while permitting effectivelyfree and independ ent rotation of the control valve and adapter by theflyweights.

2. The invention of claim 1 further comprising a control memberrotatably secured to an end of the seat member opposite the controlvalve.

3. The invention of claim 1 wherein a tubular end of the seat membersurrounds an end of the control valve, the bearing means being a thrustbearing arranged between the tubular seat member portion and the controlvalve.

4. The invention of claim 3 wherein the spring abuts the seat member andurges it toward the valve bore housing, the adapter having an annularsurface adjacent the valve bore housing, the flyweight means havinginwardly projecting arms which tend to be urged against the annularsurface by rotation of the flyweight means.

5. The invention of claim 3 wherein the tubular seat member end has anincreased diameter relative to adjacent portions of the seat member, thetubular end being formed of generally diametrically segmented portionsand further comprising means for securing the segmented portionstogether.

